Improve pair_lock handling

freqtrade/strategy/interface.py

@@ -168,12 +168,25 @@ class IStrategy(ABC):
         """
         Locks pair until a given timestamp happens.
         Locked pairs are not analyzed, and are prevented from opening new trades.
+        Locks can only count up (allowing users to lock pairs for a longer period of time).
+        To remove a lock from a pair, use `unlock_pair()`
         :param pair: Pair to lock
         :param until: datetime in UTC until the pair should be blocked from opening new trades.
                 Needs to be timezone aware `datetime.now(timezone.utc)`
         """
+        if pair not in self._pair_locked_until or self._pair_locked_until[pair] < until:
             self._pair_locked_until[pair] = until
 
+    def unlock_pair(self, pair) -> None:
+        """
+        Unlocks a pair previously locked using lock_pair.
+        Not used by freqtrade itself, but intended to be used if users lock pairs
+        manually from within the strategy, to allow an easy way to unlock pairs.
+        :param pair: Unlock pair to allow trading again
+        """
+        if pair in self._pair_locked_until:
+            del self._pair_locked_until[pair]
+
     def is_pair_locked(self, pair: str) -> bool:
         """
         Checks if a pair is currently locked

tests/strategy/test_interface.py

@@ -302,6 +302,19 @@ def test_is_pair_locked(default_conf):
     # ETH/BTC locked for 4 minutes
     assert strategy.is_pair_locked(pair)
 
+    # Test lock does not change
+    lock = strategy._pair_locked_until[pair]
+    strategy.lock_pair(pair, arrow.utcnow().shift(minutes=2).datetime)
+    assert lock == strategy._pair_locked_until[pair]
+
     # XRP/BTC should not be locked now
     pair = 'XRP/BTC'
     assert not strategy.is_pair_locked(pair)
+
+    # Unlocking a pair that's not locked should not raise an error
+    strategy.unlock_pair(pair)
+
+    # Unlock original pair
+    pair = 'ETH/BTC'
+    strategy.unlock_pair(pair)
+    assert not strategy.is_pair_locked(pair)